<!--
  speedy-vision.js
  GPU-accelerated Computer Vision for JavaScript
  Copyright 2020-2024 Alexandre Martins <alemartf(at)gmail.com>

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at
  
      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

  best-features.html
  Find & select the best features
-->
<!doctype html>
<html>
    <head>
        <meta charset="utf-8">
        <meta name="description" content="speedy-vision.js: GPU-accelerated Computer Vision for JavaScript">
        <meta name="author" content="Alexandre Martins">
        <title>Find the best keypoints</title>
        <link href="demo-base.css" rel="stylesheet">
        <script src="demo-base.js"></script>
        <script src="../dist/speedy-vision.js"></script>
    </head>
    <body>
        <h1>Find the best keypoints</h1>
        <form autocomplete="off">
            <div>
                Give me the
                <select id="feature-limit">
                    <option value="50">50</option>
                    <option value="100">100</option>
                    <option value="200">200</option>
                    <option value="300">300</option>
                    <option value="500">500</option>
                    <option value="800" selected>800</option>
                    <option value="1200">1200</option>
                    <option value="1600">1600</option>
                    <option value="2000">2000</option>
                </select>
                best keypoints (corner response function)
            </div>
            <div class="separator"></div>
            <div>
                <label for="sensitivity">Sensitivity</label>
                <input type="range" min="0.0" max="0.99" value="0.9" step="0.01" id="sensitivity">
            </div>
            <div>
                <label for="speed-slider">Video speed</label>
                <input type="range" id="speed-slider" min="0.10" max="2" value="1" step="0.01">
            </div>
            <div>
                <label for="multiscale">Multi-scale</label>
                <input type="checkbox" id="multiscale">
            </div>
        </form>
        <div>
            <span id="status"></span>
            <canvas id="canvas-demo"></canvas>
        </div>
        <div>
            <button id="play">Play / pause</button>
        </div>
        <video id="video"
            poster="../assets/loading.jpg"
            width="640" height="360"
            loop muted autoplay playsinline hidden
            title="Free to use video by Free Videos, https://www.pexels.com/pt-br/foto/853889/">
                <source src="../assets/people.webm" type="video/webm" />
                <source src="../assets/people.mp4" type="video/mp4" />
        </video>
        <script>
window.onload = async function()
{
    // form elements
    const multiscale = document.getElementById('multiscale');
    const sensitivity = document.getElementById('sensitivity');
    const featureLimit = document.getElementById('feature-limit');
    const speedSlider = document.getElementById('speed-slider');
    const playButton = document.getElementById('play');

    // load the video
    const video = document.getElementById('video');
    const media = await Speedy.load(video);

    // create the pipeline
    const pipeline = Speedy.Pipeline();
    const source = Speedy.Image.Source();
    const greyscale = Speedy.Filter.Greyscale();
    const pyramid = Speedy.Image.Pyramid();
    const detector = Speedy.Keypoint.Detector.Harris();
    const clipper = Speedy.Keypoint.Clipper();
    const sink = Speedy.Keypoint.Sink();

    source.media = media;
    detector.capacity = 8192;

    source.output().connectTo(greyscale.input());
    greyscale.output().connectTo(pyramid.input());
    pyramid.output().connectTo(detector.input());
    detector.output().connectTo(clipper.input());
    clipper.output().connectTo(sink.input());
    pipeline.init(source, greyscale, pyramid, detector, clipper, sink);

    // Main loop
    (function() {
        const canvas = setupCanvas('canvas-demo', media.width, media.height, video.title);
        let keypoints = [], frameReady = false;

        async function update()
        {
            detector.levels = multiscale.checked ? 6 : 1; // multiscale?
            detector.quality = 1.0 - Number(sensitivity.value); // adjust sensitivity
            clipper.size = Number(featureLimit.value); // cap the number of keypoints

            const result = await pipeline.run();
            keypoints = result.keypoints;

            frameReady = true;
            setTimeout(update, 1000 / 60);
        }
        update();

        function render()
        {
            if(frameReady) {
                renderMedia(media, canvas);
                renderKeypoints(canvas, keypoints);
            }

            frameReady = false;
            requestAnimationFrame(render);
        }
        render();

        setInterval(() => renderStatus(keypoints), 200);
    })();

    // misc
    playButton.onclick = () => video.paused ? video.play() : video.pause();
    speedSlider.oninput = () => video.playbackRate = speedSlider.value;
}
        </script>
        <section id="speedy-vision">
            <span>Powered by <a href="https://github.com/alemart/speedy-vision" target="_blank">speedy-vision.js</a></span>
            <a href="https://github.com/sponsors/alemart" target="_blank" class="button">
                <img alt="GitHub Sponsors" src="https://img.shields.io/github/sponsors/alemart?style=for-the-badge&logo=github&label=Sponsor&labelColor=royalblue&color=gold">
            </a>
        </section>
    </body>
</html>